• Decapods, including lobsters, crayfish, crabs, and shrimp,
are among the largest crustaceans.
– The cuticle is hardened with calcium carbonate
– The exoskeleton over the cephalothorax forms a shield
called the carapace
While most decapods are marine, crayfish live in
freshwater and some tropical crabs are terrestrial as
adults.
• Related to decapods, krill are shrimplike planktonic
organisms that reach about 3 cm long.
A major food source for whales and other ocean
predators, they are now harvested extensively by
humans for food and agricultural fertilizer.